1. Field of the Invention
This invention relates to a non-alcoholic, aqueous mouthwash composition. More particularly, the present invention relates to a non-alcoholic mouthwash composition which exhibits a homogeneous, uniform appearance and a high degree of bactericidal efficacy.
2. Description of the Art
Mouthwashes and oral rinse compositions have been used for many years and the art is replete with various compositions and formulations. Ordinarily, mouthwashes have been designed to clean the oral cavity, provide fresh breath and kill harmful bacteria. It is generally necessary to kill certain oral bacteria that contribute to malodor or secrete acidic residues which are harmful to teeth and aid in the development of gingivitis and periodontal disease.
Conventional mouthwashes contain a fairly high percentage of ethyl alcohol ranging from 10% to 30% by weight of the total composition. This alcohol is used both as a disinfectant and as a solvent in which other additives such as flavoring oils, color additives, fluorides and astringents can be dissolved and then dispersed into the aqueous solution. In fact, more than 95% of commercial mouthwash compositions contain greater that 15% by weight alcohol. These high concentrations of ethyl alcohol are primarily used to kill oral bacteria since lower concentrations are generally adequate to disperse the additives into the aqueous solution.
However, the use of alcohol in mouthwash compositions has detrimental or undesirable side effects for many user groups. For example, many people cannot tolerate alcohol and must, for medical and health reasons, avoid the use of mouthwash compositions containing alcohol. Further, young children and persons over the age of sixty are extremely susceptible to health risks when ingesting large quantities of alcohol. Generally, recovering alcoholics must avoid oral contact with alcohol as well as persons of certain religious beliefs. Last, those persons afflicted by dry-mouth syndrome or using certain medications, often prefer to avoid alcohol containing mouthwash compositions since the alcohol tends to remove moisture from the oral tissues and complicate the dry-mouth syndrome or feeling.
Various attempts have been made at developing non-alcoholic mouthwashes. For example, U.S. Pat. No. 4,919,918 to Cole et al and U.S. Pat. No. 4,971,785 to Wilson et al are directed to a non-alcoholic delivery system which can be used in mouthwashes. However, these patents are primarily directed to dry compositions which are dissolved in water immediately prior to use. Dry compositions avoid some of the problems associated with alcohol-free aqueous compositions, namely the inability of the aqueous compositions to form homogeneous and stable products.
While there is clearly a need for a non-alcoholic mouthwash, there are few aqueous, non-alcoholic mouthwashes in ready-to-use form commercially available which can achieve acceptable bactericidal efficacy. One commercial alcohol-free mouthwash is sold under the trademark AL-FREE by Keystone Research and Pharmaceutical, Inc. of Cherry Hill, N.J. This product contains water, glycerin, propylene glycol, polysorbate 20 and 80, cetyl-pyridinium chloride, flavors, sweeteners, and coloring agents. However, this product does not exhibit a high level of bactericidal efficacy.
While surfactants would normally be employed to achieve dispersion of the water insoluble additives, their use is limited in the present application. The use of various surfactants or surface active agents to achieve and maintain sufficient dispersion of the water insoluble components, particularly the flavoring oil, have been found to inhibit the activity of certain antimicrobial agents. Since the use of surfactants is deleterious to the activity of certain antimicrobial agents and thus, to achieving acceptable bactericidal efficacy, there are currently no known commercially available, ready-to-use alcohol-free, aqueous mouthwashes which effectively kill harmful microorganisms.
Accordingly, a significant problem encountered with formulating an alcohol-free mouthwash is that while the use of surfactants are necessary to achieve proper dispersion, these surfactants typically inhibit the activity of the antimicrobial agent. Thus, an alcohol-free mouthwash must have the ability to achieve sufficient bactericidal efficacy while obtaining complete dispersion of the water insoluble components in the aqueous composition. The present invention addresses this problem by the use of a specific dispersion system which results in a stable, homogeneous composition with good bactericidal efficacy. More specifically, it has been surprisingly found that certain surfactants, when used in low concentrations, can provide the necessary dispersing and stability characteristics needed in alcohol-free systems and also which do not adversely affect the activity of the antimicrobial agent employed.